jquense/yup · error · TypeError

The value of ${options.path || 'field'} could not be cast to

Error message

The value of ${options.path || 'field'} could not be cast to a value that satisfies the schema type: "${resolvedSchema.type}". 

attempted value: ${formattedValue} 
result of cast: ${formattedResult}

What it means

When a value cannot be cast into a value satisfying the schema's type, cast() throws this TypeError detailing the schema type, the attempted value, and the cast result. It wraps the underlying cast failure with debugging context including the field path from options.path.

Source

Thrown at src/schema.ts:398

    let resolvedSchema = this.resolve({
      ...options,
      value,
      // parent: options.parent,
      // context: options.context,
    });
    let allowOptionality = options.assert === 'ignore-optionality';

    let result = resolvedSchema._cast(value, options as any);

    if (options.assert !== false && !resolvedSchema.isType(result)) {
      if (allowOptionality && isAbsent(result)) {
        return result as any;
      }

      let formattedValue = printValue(value);
      let formattedResult = printValue(result);

      throw new TypeError(
        `The value of ${
          options.path || 'field'
        } could not be cast to a value ` +
          `that satisfies the schema type: "${resolvedSchema.type}". \n\n` +
          `attempted value: ${formattedValue} \n` +
          (formattedResult !== formattedValue
            ? `result of cast: ${formattedResult}`
            : ''),
      );
    }

    return result;
  }

  protected _cast(rawValue: any, options: CastOptions<TContext>): any {
    let value =
      rawValue === undefined
        ? rawValue

View on GitHub (pinned to ff31eee8a2)

Solutions

1. Validate the input first with schema.isValid()/validate() before calling cast()
2. Ensure the value can be coerced: numbers accept numeric strings, undefined via default()
3. Allow the failing case explicitly with .nullable(), .default(), or .typeError()
4. Fix upstream data so it matches the expected type

Example fix

// before
const n = yup.number().cast('abc'); // throws
// after
const parsed = yup.number().cast('42'); // 42
const safe = parsedInput !== undefined ? yup.number().cast(parsedInput) : undefined;

const ok = await schema.isValid(rawInput);
const value = ok ? schema.cast(rawInput) : undefined;

function isCastable(schema: yup.AnySchema, v: unknown): boolean {
  try { schema.cast(v); return true; } catch { return false; }
}

let value;
try { value = schema.cast(input); } catch (e) { if (e instanceof TypeError) value = schema.getDefault(); else throw e; }

When it happens

Trigger: yup.number().cast('abc'), cast(null) on a schema with no nullable(), or casting an object into a string schema; also occurs when custom cast functions return invalid values.

Common situations: Casting untrusted form/querystring input where the value is a string like 'not-a-number'; deserializing JSON where a field's type drifted; calling cast() before validating user data.

Related errors

• Only valid options for round() are: ${avail.join(', ')}
• You cannot `concat()` schema's of different types: ${this.ty
• `test` is a required parameters
• Exclusive tests must provide a unique `name` identifying the
• Must include `key` or `index` for nested validations

AI-assisted analysis of jquense/yup@ff31eee8a2 (2026-08-31). Data as JSON: /api/errors/e91042ca4dc80cc9. Report an issue: GitHub.